Leucine Codon

Question 1

Leucine UUA codon

Answer 1

UUA is rare in Streptomyces and requires the specialized tRNA encoded by bldA for translation. It regulates genes involved in secondary metabolite production.

Question 2

Gene containing leucine codon

Answer 2

bldA gene, whose tRNA is regulated only to be expressed in certain conditions.

Question 3

Example for UUA regulation

Answer 3

Streptomyces coelicolor contains redD gene, which regulates undecylprodigiosin production and contains UUA codon, but this is inhibiited unless bldA is functional.

Question 4

AdpA

Answer 4

Critical transcriptional regulator as part of A-factor signalling initiated by y-butyrolactone (quorum sensing).

Question 5

What does AdpA regulate?

Answer 5

Morphological differentiation as well as secondary metabolism.

Question 6

AdpA example

Answer 6

In S. griseus, AdpA regulates areial hyphae formation, by regulating genes such as sco1485 and whiE, which control chaplin proteins and spore pigment biosynthesis, dictating secondary metabolism or sporulation.

Question 7

Relationship between UUA and AdpA.

Answer 7

AdpA is translated independently of UUA but regulates downstream genes for bldA expression.

Question 8

Why is the UUA codon and its associated tRNA considered a regulatory “checkpoint”?

Answer 8

The rarity of UUA codon means its translation is tightly controlled by bldA. This allows Streptomyces to regulate secondary metabolism in response to specific developmental or environmental conditions.